Field
Embodiments of the disclosure relate generally to the field of bond stress measurement and more particularly to a method for use of piezochromic fluorescing materials embedded within a composite bond line illuminated with light, having a wavelength less than the fluorescent wavelength allowing measurement of a wavelength at which the maximum intensity occurs and a wavelength shift at the maximum intensity for determination of average stress on the bond.
Background
Composite materials are used in many structural applications throughout the aerospace and automotive industries. Many present and expected future products for commercial aircraft make extensive use of composite materials. Present practice connects composite components with fasteners of different types. It would be an improvement in simplicity of design, costs could be lowered, and improved protection against lightning strikes obtained by bonding different composite components together using adhesive. However, inspection techniques for evaluation of the health of such bonds in a nondestructive manner are not available.
It is therefore desirable to provide a method for evaluating bonds between layers of composite materials which is efficient, effective and can be accomplished in a non-destructive manner.